A special annotation intended solely for representing the bottom type in
the qualifier hierarchy.
This qualifier is only used automatically if the existing qualifiers do not have a
bottom type.
Other type systems could reuse this qualifier instead of introducing their own
dedicated bottom qualifier. The programmer would then use methods like
TreeAnnotator.addTreeKind(Tree.Kind, AnnotationMirror)
to
add implicit annotations and needs to manually add the bottom qualifier to the
qualifier hierarchy.
Programmers cannot write this qualifier in source code.